Technical Field
The present invention relates to network architectures, and more particularly, to software defined, scalable, hybrid packet/circuit switching architectures for data centers.
Description of the Related Art
Many data center applications are bandwidth-intensive, and as such, the data center network (DCN) is a limiting factor in the performance of the data center applications. For example, a virtual machine migration application in cloud computing (e.g. Amazon Elastic Compute Cloud (EC2) application) requires a large amount of bandwidth resources for a significant time duration; and The MapReduce applications in a Hadoop system may generate one-to-many, many-to-one and all-to-all communication patterns among servers in the Map phase and Reduce phase. The different types of communication requirements impose challenges to the data center networks, which generally end-up as a significant source of Capital Expenditure (CAPEX) and Operational Expenditure (OPEX) in overall data center construction.
Currently, several different network architectures are employed to handle the heterogeneous communication requirements within a data center. One method for the construction of a large scale DCN is the continuous “scaling up” of the hierarchical tree network, where the leaves of the tree (e.g., the top of the rack (TOR) switches) stay with low-cost commodity switches, while the higher hierarchies of the tree employ more high-end switches. Despite the high cost of the high-end electrical switches, their high line-rate features are generally enabled by high speed serializer/deserializer (SerDes) and parallel high-speed electrical connections. Such connections are limited by distance, Printed Circuit Board (PCB) layout, Input/Output (I/O) port densities and power dispatch, etc. Therefore, the continuous “scaling up” of high-end electrical switches is extremely difficult, if not impossible, from the technical point of view.
Another method currently employed is to “scale out” rather than to “scale up” the DCN, which means the use of commodity switches to build a Fat-Tree network in order to increase the network scalability. The Fat-Tree network is essentially a folded CLOS network which inherits both the benefits and drawbacks of the CLOS network (e.g., an advantage is that the network can be built as a non-blocking switch which scales up to very large port count, and a drawback is that the number of small commodity switches required scales at the same pace with the number of servers the Fat-Tree can support). The advantages of the Fat-Tree network make the large-size DCN technically feasible, but the drawbacks of it still leave the cost of building and operating a relatively large DCN prohibitively high.